The invention relates to a method for introducing fuel into the combustion chamber of an internal combustion engine wherein compressed gas is drawn from the combustion chamber during the compression phase of a working cycle, mixed with fuel in a mixing chamber, and injected into the combustion chamber together with the fuel during the subsequent working cycle.
Ever stricter requirements as regards fuel consumption and exhaust emissions, in particular hydrocarbon emission, have led to the use of new technologies for internal combustion engines. With the modern system of external mixture formation employed in internal combustion engines of the Otto type, such as injection by means of a suction pipe or use of a carburetor, part of the mixture admitted into the combustion chamber and cylinder flows into the exhaust passage of the engine during the phase of valve overlap, i.e., when intake and outlet valves are simultaneously open. Furthermore, unburnt hydrocarbons found in the exhaust passage often belong to parts of the mixture coming from annular gaps or wall areas where no combustion occurs. These shortcomings are even increased by the need for rendering the cylinder charge homogeneous, which will prevent further reduction of fuel consumption without charge stratification, i.e., a locally concentrated distribution of the mixture in the combustion chamber and the cylinder.